Study On The Growth Characteristics And Inhibition Of Microcystis

The eutrophication of water can lead to large-scale outbreak of cyanobacterial blooms,and Microcystis is one of the most common cyanobacteria.Inhibiting cyanobacteria and controlling eutrophication are important areas and research hotspots in water body repair research.Based on the investigation of surface eutrophication and surrounding environment in Wuhan,this study selected the dominant algae of Microcystis aeruginosa in Wuhan as experimental algae,the effects of light,pH,nitrogen to phosphorus ratio,nitrogen and phosphorus on environmental growth were explored,the algae-reducing effect of three kinds of leaves,such as eucalyptus,mulberry and willow was studied.Finally,combined with scanning electron microscopy(SEM),liquid chromatography(HPLC)and infrared spectroscopy(FTIR).The analysis of allelochemicals in leaf extracts by various means,the mechanism of planting allelopathic inhibition of Microcystis faecalis growth was investigated.The mechanism of plant sensitization inhibiting the growth of Microcystis aeruginosa was preliminarily investigated.The research results have reference value for the restoration of eutrophic surface water in Wuhan,and it is also useful for other areas.The main research contents and results of the thesis are as follows:(1)The eutrophic algae in Wuhan mainly include: green algae,diatoms and cyanobacteria,and the most harmful algae are Microcystis in the cyanobacteria.The most harmful algae are Microcystis in the cyanobacteria.The plants around the lake where algae are not found are mainly willows.(2)The effect of eutrophic element nitrogen or phosphorus on the growth and reproduction of Microcystis aeruginosa: in the absence of phosphorus,the higher the nitrogen concentration,the faster the algae cells grow,but when the concentration reaches 0.3g/L,the nitrogen concentration is increased,Little effect on the growth of algae cells.In the absence of nitrogen,the higher the phosphorus concentration,the faster the algae cells grow,but when the concentration reaches 0.007g/L,the increase of phosphorus concentration has little effect on the growth of algae cells.Phosphorus promotes algal cell growth at a lower concentration relative to nitrogen.(3)The effect of nitrogen-phosphorus ratio,pH value and light on the growth and reproduction of Microcystis aeruginosa: the ratio of nitrogen to phosphorus is suitable for the growth of Microcystis aeruginosa between 2:1 and 8:1,and the high nitrogen to phosphorus ratio inhibits the growth of algae cells.Algae cells grow fastest at pH 7.1,and growth of algae cells is inhibited when pH is below 7.Appropriate shading will promote the growth of algae cells,but will inhibit the growth of algae cells when the shading rate is higher than 60%.(4)Orthogonal experimental results of environmental factors: the primary and secondary factors affecting the growth of Microcystis aeruginosa are light intensity-pHnitrogen-phosphorus ratio,and the ratio of nitrogen to phosphorus is 32:1,the pH is 5,and the shading rate is 80%,which is the most unfavorable combination of growth of Microcystis.(5)The algae-inhibiting effect of three kinds of leaves: three kinds of leaf extracts have inhibitory effects on Microcystis velutipes,and the higher the concentration,the greater the inhibition effect,the degree of inhibition is: willow leaves> eucalyptus leaves> constitutive leaves,the maximum inhibition rate of algae cells by the extract of willow leaves at a concentration of 0.2g/L was 90.36%.On the seventh day,the semi-inhibitory concentrations of these three leaves against Microcystis aeruginosa were 631 mg/L,1258 mg/L,and 501 mg/L,respectively.(6)Preliminary mechanism analysis indicated that the allelochemicals(phenols and flavonoids)in the three leaf extracts could bind to the representative functional groups in the algae cells to destroy the cell membrane of the algae cells and decompose them.